Corn is processed for many purposes including industrial uses and for human and animal consumption. Corn comprises starch (referred to as the carbohydrate or sugar component), protein, fat (also referred to as oil) and fiber. One significantly expanding use is the production of ethanol from corn with the resulting ethanol being used, as an example, as a substitute for petroleum fuel. The so-called Dry Grind method is the most popular method used to produce ethanol today. About 70% of the currently produced ethanol in the U.S. is made by this method and the trend throughout the country is pointing to an overall increase in ethanol production and concomitant increase in use of this Dry Grind process.
In the Dry Grind process, starch is converted to ethanol. The corn is first ground into corn flour with water then added to form a slurry. The slurry is treated in the presence of enzymes to convert the sugars to glucose. The glucose is fermented using yeast to produce crude ethanol. The crude ethanol-water mixture is distilled to yield purified ethanol.
From the distillation step, the solids or “grains” coming out of the distilling column are referred to as distillers grains. The water coming out of the distillation column is evaporated and the resulting “solubles” are mixed with the distillers grains. This mixed combination is commonly known as distillers grains with solubles. After these are dried, they are referred to as dry distillers grains with solubles (DDGS).
DDGS consists mostly of corn minus the starch component. The remaining components are protein, fat (i.e., oil), fiber and some residual starch. Protein content is approximately 25-29%, fat about 10-11%, and from about 7-9% of the DDGS is moisture.
DDGS lysine value is approximately 0.9% compared to 3.0% for soybean meal. Its high bypass protein and high fat content make it ideal dairy cattle feed. Its high bypass protein is ideal for beef cattle but the high fat content is problematic. The high bypass protein, high fat, high fiber and low lysine make it a poor quality swine/poultry feed. By removing the fat content, DDGS can be fed in much higher rations to beef cattle.